Rapid determination method for degreasing degree of vehicle body surface

Abstract

The invention relates to a method for rapidly measuring the degreasing degree of the surface of a vehicle body. The method comprises the following steps: a) dissolving fluorescein in a first organic solvent to provide a first reagent; b) providing a bromine-containing second organic solvent as a second agent; c) applying a first reagent to the surface of the metal panel to ensure that the surface of the metal panel is completely covered by the first reagent; and d) putting the metal panel treated in the step c) into a container filled with a second reagent, enabling the fluorescein in the first reagent to be in contact with bromine, especially bromine steam in the second reagent to show color change from crimson to red to pink, and then irradiating the metal panel through an ultraviolet lamp. When grease exists on the metal panel, an unsaturated compound in the grease and bromine are subjected to an addition reaction, except that the dark red changes to red to pink, fluorescence phenomenon occurs, and when grease does not exist on the metal panel, the dark red changes to red to pink, and fluorescence phenomenon does not occur.

Description

Technical Field

[0001] The invention belongs to the technical field of metal materials, and in particular relates to a method for evaluating the amount of grease residue on the surface of a metal material. Background Art

[0002] The first process in the automobile body-in-white painting workshop is to degrease the body-in-white, which is to remove impurities such as grease and metal chips adhering to the surface of the body-in-white. If the body quality after degreasing is not up to standard, the quality of the phosphate film, passivation film and electrophoretic paint film on the surface of the body-in-white will often fail to meet the production standards, which will increase labor costs and affect the service life of the vehicle. This phenomenon is not allowed in some high-end models.

[0003] In actual production, in order to evaluate the degreasing degree of the degreasing process, corresponding methods are often needed. At present, there are two mainstream evaluation methods in the production site. The first is to rinse the degreased plate with water. If the continuity of the water film is good, it means that the degreasing degree is high. If the continuity of the water film is poor, it means that the degreasing effect is poor. The second method is mainly to wipe the degreased plate with a clean rag and then observe the cleanliness of the rag surface, but this method can only serve as a supplement to the first method.

[0004] The above two methods can be applied in the production process mainly because they are simple to operate and can provide the fastest guidance for production. However, the above methods also have great disadvantages. The evaluation of these two methods is very subjective and there is no unified standard. In some important production practices, it is difficult for the above methods to provide scientific and accurate parameters and standards, and it is difficult to give effective guidance. Based on the above reasons, it is very necessary to develop a more scientific and systematic degreasing evaluation method. Summary of the invention

[0005] The purpose of the present invention is to provide a degreasing rate evaluation method based on color development reaction. The method is convenient and fast and more accurate than traditional methods, and can meet the needs of some production work with high accuracy requirements. The method is a rapid determination method for the degreasing degree of the body surface of an automobile body, especially an automobile body-in-white.

[0006] In a first aspect of the present invention, a method for quickly determining the degree of degreasing on the surface of a metal panel is provided, the method comprising the following steps:

[0007] a) dissolving fluorescein in a first organic solvent to provide a first reagent;

[0008] b) providing a bromine-containing second organic solvent as a second reagent;

[0009] c) applying the first agent to the surface of the metal panel to ensure that the surface of the metal panel is completely covered by the first agent;

[0010] d) placing the metal panel treated in step c) in a container containing a second reagent, and after the fluorescein in the first reagent contacts the bromine in the second reagent, especially bromine vapor, the metal panel changes color from deep red to red to pink, and then irradiates with an ultraviolet lamp.

[0011] If there is grease on the metal panel, the unsaturated compounds in the grease will react with bromine, and in addition to the transformation of the deep red to red to pink, there will also be fluorescence.

[0012] If no grease is present on the metal panel, the transition from deep red to red to pink is not accompanied by fluorescence.

[0013] The color reaction of "changing color from deep red to red to pink" actually involves the reaction of bromine, especially bromine vapor, with fluorescein to form tetrabromofluorescein. When the color turns pink and no longer changes, it means that the fluorescein has been completely reacted with bromine, especially bromine vapor, to form tetrabromofluorescein. The above process needs to last for a sufficient time, for example, 1-60 minutes, preferably 30-60 minutes, more preferably 30-50 minutes, and most preferably 30 minutes. If the color change is not complete, it means that some fluorescein has not been completely converted into tetrabromofluorescein. In this case, the fluorescein that is not completely converted and exists alone will have a fluorescent reaction, making it impossible to correctly evaluate the presence of oil.

[0014] Preferably, the fluorescein is fluorescein with CAS number 518-45-6, molecular formula: C 20 H 12 O5, molecular weight: 332.31, appearance: yellow solid, purity: >95%, solubility: soluble in DMSO, DMF, DCM, etc., storage conditions: protected from light, dry, stored at -20℃.

[0015] Preferably, the first organic solvent comprises a saturated aliphatic alcohol having C1-C8 carbon atoms, more preferably a saturated aliphatic alcohol having C1-C4 carbon atoms, most preferably ethanol; the second organic solvent comprises a halogenated hydrocarbon solvent, preferably carbon tetrachloride.

[0016] Preferably, in step b), the concentration of bromine is 1%-30%, preferably 1%-10%, more preferably 3%-6%, most preferably 5%, in terms of mass percentage.

[0017] Preferably, in the step a), the weight-to-volume ratio of the fluorescein to the first organic solvent is 1:1.

[0018] Preferably, in step d), the bromine comprises bromine vapor.

[0019] Preferably, in step d), the metal panel treated in step c) is placed in a container containing the second reagent in a suspended manner, so that the sample in the second reagent cannot contact any other reagents.

[0020] In a second aspect of the present invention, there is provided a developer composition for use in the above method, comprising:

[0021] a first reagent comprising fluorescein and a first organic solvent, and

[0022] A second reagent comprises bromine and a second organic solvent.

[0023] Preferably, the fluorescein is fluorescein with CAS number 518-45-6, molecular formula: C 20 H 12 O5, molecular weight: 332.31, appearance: yellow solid, purity: >95%, solubility: soluble in DMSO, DMF, DCM, etc., storage conditions: protected from light, dry, stored at -20℃.

[0024] Preferably, the first organic solvent comprises a saturated aliphatic alcohol having C1-C8 carbon atoms, more preferably a saturated aliphatic alcohol having C1-C4 carbon atoms, most preferably ethanol; the second organic solvent comprises a halogenated hydrocarbon solvent, preferably carbon tetrachloride.

[0025] Preferably, in the second reagent, the concentration of bromine is 1%-30%, preferably 1%-10%, more preferably 3%-6%, most preferably 5%, in terms of mass percentage.

[0026] Preferably, in the first reagent, the weight-to-volume ratio of the fluorescein to the first organic solvent is 1:1.

[0027] In a third aspect of the present invention, there is provided a use of the developer composition for rapidly determining the degree of degreasing on the surface of a metal panel.

[0028] In a preferred embodiment of the present invention, the method for rapidly determining the degree of degreasing on the surface of a vehicle body of the present invention comprises the following steps:

[0029] (1) Prepare a color developer: dissolve 100 mg of fluorescein in 100 mL of alcohol to form reagent a. Reagent b is a 5% (by mass percent) bromine-containing carbon tetrachloride solution.

[0030] (2) Take the metal plate to be tested and spray the surface of the plate with reagent a, controlling the distance between the nozzle and the plate to be 15-40 cm to ensure that the plate is fully covered by reagent a.

[0031] (3) Coloring treatment: Hang the metal plate treated in step (2) in a container containing reagent b, so that the bromine vapor evaporated from the bromine-containing carbon tetrachloride solution is in full contact with the surface of the plate; the fluorescein in reagent a will react with bromine to produce a color ranging from deep red to red to pink, and this color change will not be accompanied by a fluorescent reaction in the absence of grease. The reaction time of the plate in bromine vapor is controlled to be 1-60 minutes, and the reaction temperature is controlled to be between 10-50°C.

[0032] (4) UV irradiation: UV light is used to irradiate the metal plate treated in step (3). When grease is present, the unsaturated compounds in the grease will react with bromine, such as bromine vapor, to generate an addition reaction. In addition to the previous deep red color changing to red or pink, a fluorescence reaction will also occur. The yellow fluorescence is distributed in a dotted pattern on the surface of the plate along with the grease. The distribution range and area of ​​the yellow fluorescence on the plate are positively correlated with the surface grease content.

[0033] In the above step (1), fluorescein, alcohol (ethanol), bromine and carbon tetrachloride are all commercially available and of analytical grade.

[0034] In the above step (3), the reaction time can be judged by the color change of the board surface. That is, when the board surface is observed to completely turn pink and the pink background does not deepen with time, it means that the coloring reaction is completed.

[0035] In the above step (4), the ultraviolet lamp used is a UVLMS-38 three-wavelength ultraviolet lamp.

[0036] In the present invention, the unsaturated compounds in the oil are unsaturated higher fatty acid glycerides and saturated higher fatty acid glycerides, and the fluorescein-bromine developer can react with the unsaturated compounds in the oil, and the product of the reaction has a fluorescent reaction. The metal panel is irradiated with an ultraviolet lamp, and the reaction degree of the degreasing process can be obtained according to the number of fluorescent points.

[0037] Compared with the prior art, the advantages of the present invention are:

[0038] The method for evaluating the degreasing rate of the vehicle body surface provided by the present invention can obtain the test results immediately after the test, which is convenient and quick and will not affect the actual production rhythm. The reagents used for the treatment include alcohol, fluorescein, and bromine-containing carbon tetrachloride solution, and the reagents are simple, easy to obtain and reusable. Its detection limit is about 5 micrograms, which can provide the most accurate test results. The test can only derive the degree of degreasing reaction through color changes, and has low requirements on the professional skills of on-site operators. The method for evaluating the degreasing rate of the vehicle body surface provided by the present invention is simple and feasible, and can provide a scientific and reliable degreasing evaluation method for actual production. It should be noted that gloves need to be worn throughout the entire processing process to prevent grease from being carried on the palms and affecting the results of the experiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 : Optical image (a) of a degreased plate treated with the developer of the present invention.

[0040] Figure 2 : Optical image (b) of a plate that has not been fully degreased after being treated with the developer of the present invention.

[0041] Figure 3 : Optical picture (c) of a degreased plate treated with the developer of the present invention and then irradiated with ultraviolet light.

[0042] Figure 4 : An optical picture (d) of a plate that has not been fully degreased after being treated with the developer of the present invention and then irradiated with an ultraviolet lamp. DETAILED DESCRIPTION

[0043] The following examples are merely illustrative of embodiments of the present invention and are not intended to limit the scope of the present invention in any way.

[0044] The metal panel used in the embodiment of the present invention is an aluminum alloy panel.

[0045] Example 1.1 - Grease-exposed metal panel

[0046] (1) Prepare a color developer by dissolving 100 mg of fluorescein in 100 mL of alcohol to form reagent a. Reagent b is a 5% (by mass percent) bromine solution in carbon tetrachloride.

[0047] (2) Take an aluminum alloy plate that has not been degreased, spray the surface of the plate with reagent a, and control the distance between the nozzle and the plate to be 30 cm to ensure that the panel is fully covered by reagent a.

[0048] (3) Coloring treatment: hang the metal panel treated in step (2) in a container containing reagent b, control the reaction time to 30 min, and the reaction temperature to 35° C. to allow the bromine vapor to fully react with the panel surface.

[0049] (4) UV light irradiation: The metal panel treated in step (3) is irradiated with UV light. Fluorescence will be present after UV light irradiation, indicating that there is grease on the surface of the sample.

[0050] Example 1.2 - Degreased metal panel

[0051] (1) Prepare a color developer by dissolving 100 mg of fluorescein in 100 mL of alcohol to form reagent a. Reagent b is a 5% (by mass percent) bromine solution in carbon tetrachloride.

[0052] (2) Take the aluminum alloy panel to be tested and immerse it in alcohol and aluminum alloy degreasing agent for 1 hour respectively to fully remove the grease on the surface of the aluminum alloy.

[0053] (3) For aluminum alloy panels, spray the panel surface with reagent a and control the distance between the nozzle and the panel to be 30 cm to ensure that the panel is fully covered by reagent a.

[0054] (4) Coloring treatment: hang the metal panel treated in step (3) in a container containing reagent b, control the reaction time to 30 min, and the reaction temperature to 35° C. to allow the bromine vapor to fully react with the panel surface.

[0055] (5) UV light irradiation: The metal plate treated in step (3) is irradiated with UV light. No fluorescence is observed after UV light irradiation, indicating that there is no grease on the surface of the sample.

[0056] It can be seen from Examples 1.1 and 1.2 that fluorescence will only be present when exposed to ultraviolet light if there is grease on the metal panel. That is, after the developer is sprayed on the metal panel, bromine vapor reacts fully with the developer-sprayed metal panel, and then the developer is exposed to ultraviolet light, fluorescence will be present if there is grease on the panel.

[0057] Comparative Example 1 - Metal panel not treated with developer

[0058] (1) Take an aluminum alloy panel that has not been degreased, spray the panel surface with alcohol, and control the distance between the nozzle and the panel to be 15-40cm to ensure that the panel is fully covered by alcohol.

[0059] (2) UV light irradiation: The metal plate treated in step (1) is irradiated with UV light. It is found that no fluorescence phenomenon exists after UV light irradiation.

[0060] From the comparison between Comparative Example 1 and Example 1.1, it can be seen that the developer of the present invention needs to be used and applied to a metal panel with grease. The fluorescein in the developer will react with bromine to produce a dark red-red-pink color, and the bromine in the developer, especially bromine vapor, will react with the unsaturated compound in the grease and the product of the addition reaction will react with fluorescence. When the metal panel is irradiated with ultraviolet light, fluorescence will appear.

Claims

1. A method for rapidly determining the degree of degreasing on the surface of a metal panel, characterized in that: The method comprises the following steps: a) dissolving fluorescein in a first organic solvent to provide a first reagent; b) providing a bromine-containing second organic solvent as a second reagent; c) applying the first agent to the surface of the metal panel to ensure that the surface of the metal panel is completely covered by the first agent; and d) placing the metal panel treated in step c) in a container containing a second reagent, and after the fluorescein in the first reagent contacts with the bromine in the second reagent, the metal panel changes color from deep red to red to pink, and then irradiates with an ultraviolet lamp; When there is grease on the metal panel, the unsaturated compounds in the grease will react with bromine, and in addition to the transformation of the deep red to red and pink, there will also be fluorescence. When no grease is present on the metal panel, the deep red to red to pink transition is not accompanied by fluorescence.

2. The method according to claim 1, characterized in that: The fluorescein is fluorescein with CAS number 518-45-6.

3. The method according to claim 1 or 2, characterized in that: The first organic solvent includes a saturated aliphatic alcohol having C1-C8 carbon atoms, more preferably a saturated aliphatic alcohol having C1-C4 carbon atoms, and most preferably ethanol; the second organic solvent includes a halogenated hydrocarbon solvent, preferably carbon tetrachloride.

4. The method according to any one of claims 1 to 3, characterized in that In step b), the concentration of bromine is 1%-30%, preferably 1%-10%, more preferably 3%-6%, most preferably 5%, by mass percentage.

5. The method according to any one of claims 1 to 4, characterized in that In the step a), the weight-to-volume ratio of the fluorescein to the first organic solvent is 1:

1.

6. The method according to any one of claims 1 to 5, characterized in that In step d), the bromine comprises bromine vapor.

7. The method according to any one of claims 1 to 6, characterized in that In step d), the metal panel treated in step c) is placed in a container containing a second reagent in a suspended manner.

8. The developer composition according to any one of claims 1 to 7, characterized in that a first reagent comprising fluorescein and a first organic solvent, and A second reagent comprises bromine and a second organic solvent.

9. The developer composition according to claim 8, characterized in that The fluorescein is fluorescein with CAS number 518-45-6.

10. The developer composition according to claim 8 or 9, characterized in that: The first organic solvent includes a saturated aliphatic alcohol having C1-C8 carbon atoms, more preferably a saturated aliphatic alcohol having C1-C4 carbon atoms, and most preferably ethanol; the second organic solvent includes a halogenated hydrocarbon solvent, preferably carbon tetrachloride.

11. The developer composition according to any one of claims 8 to 10, characterized in that In the second reagent, the concentration of bromine is 1%-30%, preferably 1%-10%, more preferably 3%-6%, and most preferably 5%, in terms of mass percentage.

12. The developer composition according to any one of claims 8 to 11, characterized in that In the first reagent, the weight-to-volume ratio of the fluorescein to the first organic solvent is 1:

1.

13. Use of the developer composition according to any one of claims 8 to 12 for rapidly determining the degree of degreasing on the surface of a metal panel.

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